"For all of our adventure activities safety is our primary concern," he said.

"It's really our priority."

The trip along the river included 360-degree spins but it was too early to say whether a manoeuvre was involved before the crash, he said.

Sergeant Mark Gill, of Queenstown, said the boat hit a rock face, damaging the engine and rear of the craft.

Passengers were from Europe, America and New Zealand and the crash was also referred to the Department of Labour, he said.

St John Queenstown team manager Alana Reid said an ambulance took four people to the Lakes District Hospital.

All four were Queenstown residents, two women, both 20, a 26-year-old man and a 59-year-old woman. Their injuries ranged from back pain to traumatic chest pain after one of the group hit a rail in the boat, she said.

The remaining passengers were taken to the Shotover Jet beach at Arthurs Pt, where another ambulance was waiting.

One member of the group, a 60-year-old American male tourist, was taken to Lakes District Hospital suffering from whiplash, she said.

A Maritime New Zealand spokeswoman said the agency was gathering information and a decision was expected today on whether a full investigation was necessary.

Queenstown Lakes District Council harbourmaster Marty Black said he could not comment on the cause of the crash.

"We have to work our way through it," he said.

The section of the Shotover River where the boat crashed is a class two gorge, with moderate rapids.